We propose to develop, analyze, implement and test a novel approach for tracking single particles in a scanning force microscope. The ability to study the dynamics of single molecules and of the interactions between molecules is a critical component for continued progress in molecular biology and for understanding and treating a variety of genetic diseases. Current techniques include using single particle tracking in optical microscopy and position tracking in optical traps. Particle tracking in optical microscopy is limited in its temporal resolution. Optical traps can provide superb spatial and temporal resolution;the construction of systems with such sensitivity, however, is extremely challenging. Due to the exquisite spatial resolution of scanning force microscopy as well as its ability to operate in liquid, it has become a standard tool for studying the structure of single molecules. The standard approach for studying dynamics is the use of time-lapse imaging. Each image can take seconds to minutes to acquire and thus the applicability of this approach is extremely limited. The exploratory research in this proposal is focused on developing feedback control algorithms for an atomic force microscope to directly track a single molecule such as a motor protein or a polymerase. We aim to (1) design and test algorithms for rapidly moving the tip along a biological polymer such as RNA, microtubules, and actin, without imaging, (2) combine these algorithms with detection and estimation schemes to track molecules moving on such structures, such as molecular motors or polymerases, and (3) apply the scheme to study the motion of tryopomyosin and of myosin V along actin. PUBLIC HEALTH RELEVANCE: In this project we propose to develop a novel method for studying the dynamics of single molecules moving on biopolymers. The method is a new control approach centered on the concept of particle tracking with a scanning force microscope. It takes advantage of the high spatial resolution of scanning force microscopy and the high temporal resolution inherent in the high resonant frequencies of the cantilevers.